Biology

• Multiprotein complex, a group of two or more associated polypeptide chains
• Complex (taxonomy), in biology, a cluster of species so closely related that they intergrade, can interbreed, and are difficult to firmly distinguish except at the extremes of their ranges
• Mimicry complex, a complex system of organisms and dependencies involved in a case of mimicry

Chemistry

• Coordination complex, also called a "coordination compound" or "metal complex", a structure consisting of a central atom or molecule weakly connected to surrounding atoms or molecules (ligands)
• Chelate complex, a coordination complex with more than one bond

Mathematics

• Complex number
  Complex number
  A complex number is a number consisting of a real part and an imaginary part. Complex numbers extend the idea of the one-dimensional number line to the two-dimensional complex plane by using the number line for the real part and adding a vertical axis to plot the imaginary part...
  
  , an extension of real numbers obtained by adjoining imaginary numbers
• Complex system
  Complex system
  A complex system is a system composed of interconnected parts that as a whole exhibit one or more properties not obvious from the properties of the individual parts....
  
  , a system of interconnected simple parts that together exhibit a high degree of computational complexity from which emerges a higher order behavior
• Complex analysis
  Complex analysis
  Complex analysis, traditionally known as the theory of functions of a complex variable, is the branch of mathematical analysis that investigates functions of complex numbers. It is useful in many branches of mathematics, including number theory and applied mathematics; as well as in physics,...
  
  , the study of functions of complex numbers
• An element of a complex algebra or field of sets
• Chain complex
  Chain complex
  In mathematics, chain complex and cochain complex are constructs originally used in the field of algebraic topology. They are algebraic means of representing the relationships between the cycles and boundaries in various dimensions of some "space". Here the "space" could be a topological space or...
  
  , a (possibly long) sequence of maps
• Simplicial complex
  Simplicial complex
  In mathematics, a simplicial complex is a topological space of a certain kind, constructed by "gluing together" points, line segments, triangles, and their n-dimensional counterparts...
  
  , a kind of topological space that can be divided into fully adjacent triangles, or more generally, into simplices
• CW complex
  CW complex
  In topology, a CW complex is a type of topological space introduced by J. H. C. Whitehead to meet the needs of homotopy theory. This class of spaces is broader and has some better categorical properties than simplicial complexes, but still retains a combinatorial naturethat allows for...
  
  , or closure-finite weak complex, a kind of topological space, a generalization of the simplicial complex
• Line complex
  Line complex
  In algebraic geometry, a line complex is a 3-fold given by the intersection of the Grassmannian G with a hypersurface. It is called a line complex because points of G correspond to lines in P3, so a line complex can be thought of as a 3-dimensional family of lines in P3...
  
  , a 3-dimensional family of lines in space

Other scientific uses

• Complex (psychology)
  Complex (psychology)
  A complex is a core pattern of emotions, memories, perceptions, and wishes in the personal unconscious organized around a common theme, such as power or status...
  
  , a group of mental factors that are unconsciously associated by the individual with a particular subject and influence the individual's attitude and behavior
• Synonym for a complex system
  Complex system
  A complex system is a system composed of interconnected parts that as a whole exhibit one or more properties not obvious from the properties of the individual parts....
  
   which generally includes all interactions between elements
• Complex crater
  Complex crater
  Complex craters are a type of large impact crater morphology.Above a certain threshold size, which varies with planetary gravity, the collapse and modification of the transient cavity is much more extensive, and the resulting structure is called a complex crater...
  
  , a type of large impact crater morphology

As a name

• Complex (artist), an American Rap artist (www.youtube.com/complexlifemusic)
• Complex (band)
  Complex (band)
  Complex was a Japanese rock band composed of guitarist Tomoyasu Hotei and singer Koji Kikkawa. They released their self-titled debut in 1989, along with their first single and video, "Be My Baby"...
  
  , a Japanese rock band
• Complex (magazine), a young men's style/lifestyle magazine
• CoMPLEX (ucl) is an interdisciplinary centre at University College London into biology and biomedicine
• "Complex" (song), a song by British musician Gary Numan

See also

• The Complex (disambiguation)
• Complexity
  Complexity
  In general usage, complexity tends to be used to characterize something with many parts in intricate arrangement. The study of these complex linkages is the main goal of complex systems theory. In science there are at this time a number of approaches to characterizing complexity, many of which are...
  
  
• Complexity (disambiguation)
  Complexity (disambiguation)
  In general usage, complexity tends to be used to characterize something with many parts in intricate arrangement.Complexity may also refer to:* Complex systems* Complexity theory * Kolmogorov complexity...
  
  
• Complexity theory (disambiguation)
• Theory of complex systems
  Complex systems
  Complex systems present problems in mathematical modelling.The equations from which complex system models are developed generally derive from statistical physics, information theory and non-linear dynamics, and represent organized but unpredictable behaviors of systems of nature that are considered...
  
  
• The Military–industrial complex